System and method for improving fuel economy of a vehicle powertrain

Abstract

A controller for a vehicle may include communication channels and control logic. The communication channels may be configured to receive distance data from a proximity sensor disposed on a vehicle and to send shift commands to a transmission. The control logic may be configured to respond to distance data indicating a second vehicle disposed at a distance closer than a threshold distance while the vehicle is moving at or below a threshold speed by sending a shift command to the transmission.

What is claimed is: 
     
       1. A method of controlling a vehicle transmission comprising:
 capturing data from a proximity sensor to estimate a distance between the vehicle and an object; 
 monitoring a speed sensor to estimate a vehicle speed; 
 entering a traffic mode in response to the object being within a threshold distance of the vehicle and the vehicle speed being less than a threshold speed; and 
 while in the traffic mode with a shift selector in a drive position, shifting the transmission to a neutral state. 
 
     
     
       2. The method of  claim 1 , wherein shifting the transmission to a neutral state occurs in response to application of a brake pedal within 5 seconds after releasing the brake pedal. 
     
     
       3. The method of  claim 1 , wherein the proximity sensor is a camera. 
     
     
       4. The method of  claim 1 , further comprising while in the traffic mode, based on data from the proximity sensor, updating the estimate of the distance between the vehicle and the object. 
     
     
       5. The method of  claim 4 , further comprising exiting from the traffic mode in response to the object being farther than the threshold distance from the vehicle. 
     
     
       6. The method of  claim 5 , further comprising shifting the transmission to a drive state upon exiting the traffic mode. 
     
     
       7. The method of  claim 1 , further comprising indicating to a driver that the vehicle is operating in the traffic mode. 
     
     
       8. The method of  claim 7 , wherein operating in the traffic mode illuminates a light within the vehicle. 
     
     
       9. A vehicle comprising:
 a transmission; 
 a proximity sensor disposed on the vehicle and configured to capture distance data; and 
 at least one controller programmed to, while the vehicle is moving at a speed below a threshold speed, shift the transmission from a drive state to a neutral state in response to the distance data from the proximity sensor identifying a second vehicle disposed at a distance closer than a threshold distance from the proximity sensor. 
 
     
     
       10. The vehicle of  claim 9  wherein the proximity sensor is a camera. 
     
     
       11. The vehicle of  claim 10  wherein the controller is further programmed to increase the threshold distance in response to image data from the camera indicating a downhill slope. 
     
     
       12. The vehicle of  claim 10  wherein the controller is further programmed to increase the threshold speed in response to image data from the camera indicating a downhill slope. 
     
     
       13. The vehicle of  claim 9  wherein the controller shifts the transmission to a neutral state in response to application of a brake pedal within 5 seconds after releasing the brake pedal. 
     
     
       14. A controller for a vehicle comprising:
 communication channels configured to receive distance data from a proximity sensor disposed on a vehicle and to send shift commands to a transmission; and 
 control logic configured to respond to distance data indicating a second vehicle disposed at a distance closer than a threshold distance while the vehicle is moving at or below a threshold speed by sending a shift command to the transmission. 
 
     
     
       15. The controller of  claim 14  wherein the shift command is from a drive state to a neutral state. 
     
     
       16. The controller of  claim 14  wherein the control logic is further programmed to output a shift command from a neutral state to a drive state in response to the vehicle speed increasing above the threshold speed. 
     
     
       17. The controller of  claim 14  wherein the control logic is further programmed to output a shift command from a neutral state to a drive state when the second vehicle is disposed at a distance greater than the threshold distance. 
     
     
       18. The controller of  claim 14  wherein the control logic is further programmed to output a shift command to a neutral state in response to application of a brake pedal within 5 seconds after releasing the brake pedal. 
     
     
       19. The controller of  claim 14  wherein the proximity sensor is a camera.